the surface of contact of sphere and fluid being conducting, currents will be incited in the fluid that will pass into the sphere and out again.

In the case of the earth there is no fluid with reference to which the solid earth performs a total differential rotation; still there are partial differential rotations due to moving streams, ocean currents, tidal waves and air currents. Such a field, if it exist, can be differentiated with the aid of the potential theory.

Purely local disturbances would constitute a fourth-the anomalous field.'

We as yet have no satisfactory answer as to the origin of the earth's primary mag netic field, neither has the astronomer an answer to the query 'Whence the moon.' He, however, accepts the moon's existence and computes its disturbing effects upon the earth's motions. Just so it is with the earth's magnetism. We do not know whence it has come, but we know it is there. We know that to-day the magnetic earth is rotating about an eccentric axis, and so let us ask ourselves What is the effect of the self-inductive action of the rotating magnetic earth? How is the principle of the conservation of energy when applied to the motions of the magnetic earth to be fulfilled? L. A. BAUer.

on the magnesian limestones of the Ozark Series, and then out toward the east, at the expense of the lower members, each stratum overlapping that which is under it. In the vicinity of the limestone breccia they present the following sections: 1. Green Shale, 7 feet. 2. Shaley Limestone, 10 feet. 3. Speckled Crinoidal Limestone, 3 feet. 4. Basal Conglomeratic Sandstone, 4 inches.

Proceeding south along the west side of the valley we find the first indication of a disturbance in the form of a gentle undulation of the upper portion of the shaley limestone, No. 2 of the section. A few hundred yards further we encounter the first of a series of huge masses of breccia, consisting of the light gray, amorphous limestone and thin shale of No. 2, broken into angular fragments of various sizes, and recemented, partly by a similar substance, and partly by the subsequent infiltration of calcareous matter occurring now in the form of calcite. The original bedding planes have been mostly obliterated, and the breccia weathers out along the hillside in boulder-like masses, 10 to 20 feet thick, and 50 to 100 feet in width. A stratum of shaley limestone at the base of these masses partially retains its original appearance, and from its relation to the more massive breccia overlying it the whole is seen to have been subjected to violent contortion and

SOUTHWESTERN MISSOURI.

THE brecciated limestone which it is proposed to describe in this paper outcrops near the base of Eagle Ridge, on the west side of the valley of Dry Creek, five miles west of the town of Galena, county seat of Stone County, Missouri. The several members of the Devonian strata in this portion of the State are, in their normal condition, very regular and evenly bedded, and are perfectly conformable, from their base, to and with the overlying Kinderhook Group. They rest, with slight local unconformity,

and the positions of the pieces slightly changed, but not widely separated as they would inevitably have been had the brecciated masses been accumulated by wave action on a seashore. The hypothesis that the brecciation and contortion were produced by undermining of the strata and by subsequent crushing from the weight of the superincumbent rock is inconsistent with the facts. The lower members of the Devonian strata are undisturbed, and in the central portion even the whole of No. 2 seems to be present and perfectly horizontal and the breccia rests on it increasing the thickness of the Devonian strata from its normal 20 feet to 40 feet in the central portion of the disturbance.

In short, the only theory which will explain all the phenomena is that which has been applied, in explanation of the manner of formation of similar but vastly more extended Devonian limestone breccias in Iowa, viz., by lateral pressure produced by the creep' or sliding on a sloping sea bottom of the displaced strata immediately after their deposition.

From a study of the strike of the undulations, displacements and other attendant phenomena, it becomes evident that the pressure was applied from the northeast. The Devonian strata at present rise in that direction at a rate not exceeding 8 or 10 feet per mile, and during the Devonian age were doubtless still more nearly horizontal. It is remarkable that so slight a slope could have given rise to a sliding of a portion of the sea bottom, but it is undoubtedly the fact that, while the deposition of the Devonian strata had proceeded without interruption to the top of the shaley limestone No. 2, the upper 2 or 3 feet began to slide on the underlying stratum. About the western line of Stone county the resistance overcame the weight of the 'creeping' strata, and the tension becoming too strong, at one place certainly and perhaps at others not yet

discovered, that they suddenly gave way, were contorted, brecciated, forced forward and hurled in boulder-like masses on to other undisturbed strata.

Considering the intensity of the force and the conditions under which it was applied, it is surprising that the area of the disturbance should be so small; on the opposite side of the valley, one-eighth of a mile distant, there is not the slightest sign of it, and in the next valley, one-fourth of a mile southwest from it, the Devonian strata are undisturbed. Its areal extent cannot be greater than one-fourth square mile.

The lithification of the shaley limestone was practically complete at the time of the displacement, for the fragments are all sharply angular and must then have been very hard. And as the relation of the overlying strata shows that the period of the disturbance immediately succeeded that of deposition of No. 2, deposition and lithification must have proceeded contemporaneously.

The green shale, which is the upper member of the Devonian in this region, thins out in the hollows between the dome-shaped prominences of the surface of the breccia, and totally disappears over the higher portions of the disturbed area. The points where it is absent are not now and never were more than twenty feet higher than the surrounding sea bottom, where the green shale was deposited in very regular laminæ, without wave action. The areal distribution of the green shale is such as to show that it was deposited in a comparatively small and shallow esturine basin, connecting with the sea toward the south, and supplied with fine sediment from the land on the east and north. The limited extent of this body of water accounts for the feebleness of its waves, which did not affect the green shale at the depth of only twenty feet around the elevated area formed by the breccia. The higher prominences

of the breccia were slightly eroded by wave action during the deposition of the green shale in the surrounding water, but the leveling had not proceeded far when the Devonian age came to a close; the entire region was depressed, and the Louisiana limestone (formerly known as the Lithographic limestone), or basal member of the Kinderhook Group, was laid down over the breccia. It is usually a regularly bedded, dark gray limestone, everywhere perfectly conformable to the green shale, but over the distributed area it is irregularly bedded and slightly arched, but soon succeeded, by thickening in the hollows and thinning over the prominences, in leveling off the ancient sea bottom. The Lower Carboniferous strata are here locally unconformable with the Devonian. We have thus seen that the thinning of the green shale over the area of disturbance fixes the time of said disturbance at the period between the deposition of Nos. 1 and 2 or the shaley limestone and the green shale. From a general resemblance between the shaley limestone of this region and portions of the Cedar valley limestone of Iowa, and from the fact that this peculiar mode of brecciation obtained in both regions, I wish to suggest that the light brown or gray, amorphous, shaley limestone of southwestern Missouri may be the equivalent of the Cedar valley limestone of central Iowa.

GALENA, Mo.

OSCAR H. HERSHEY.

CURRENT NOTES ON PHYSIOGRAPHY (X.)

LEY'S CLOUDLAND.

THIS long expected work (Stanford, London, 1894. 208 p.) is an effort to establish a classification and terminology of clouds on a genetic basis. While such a plan has much to commend it, and must eventually be adopted in fully developed form, its presentation now is perhaps premature; for there is yet much to learn regarding the

origin of certain cloud forms, and much difference of opinion still prevails on the subject. Four chief classes are recognized in Ley's scheme: clouds of radiation, such as ground fogs; of inversion, such as cumulus, dependent on overturnings in an unstable atmosphere; of interfret, such as waving stratiform clouds formed at the contact of layers of different temperature; and of inclination, such as pendent cirrus wisps, caused by the settlement of particles from one atmospheric stratum into another. The illustrations, reproduced from photographs by Clayden, are for the most part excellent. The chief deficiency of the work is the absence of comparative tables, by which the terms proposed by Ley may be translated into those adopted by the International Meteorological Congress. In a number of passages exceptions must be taken to the manner of physical explanation of cloud formation, especially to statements concerning the relation of water and ice particles in cumulus and cirrus clouds, and to the repeated implication that the liberation of latent heat in the condensation of vapor actually warms the air. The chapters on the theory of atmospheric currents and on the prevailing winds of the globe are hardly relevant to the rest of the book and add little value to it. Remembering that the author has devoted years of observation to cloud study, and that latterly his work has been much interrupted by ill health, it is doubly a regret that his book cannot be more highly commended.

BUREAU CENTRAL MÉTÉOROLOGIQUE. THE latest series of Annales of this important Bureau contain as usual a volume of memoirs in which, besides the statistical studies of thunder storms in France by Fron and several reports of magnetism, there are essays by Angot on the advance of vegetation and the migration of birds in France for ten years, 1881-1890, and on the meteor

ological observations on the Eiffel tower during 1892; and by Durand-Gréville on squalls and thunderstorms. Nearly all the features of the advance of vegetation exhibit the accelerating influence of the Mediterranean and the retarding influence of the Bay of Biscay. The records of the Eiffel tower are chiefly interesting in showing inversions of nocturnal temperature in the means of all the months, and consequently in proving a distinct variation in the diurnal values of the vertical temperature gradient in the lower atmosphere; as well as a change of the time of maximum wind velocity from afternoon at surface stations to night at the top of the tower. Durand-Gréville's essay is illustrated by an excellent chart of the distribution of pressure during an extended squall that occurred on August 27, 1890; the isobars being drawn for every millimeter, and showing a sharp N-like double bend at the place of the squall.

WINTER STORMS IN THE NORTH SEA.

THE famous Christmas storm of 1821, which led Brandes and Dove to their early statements concerning the system of storm winds, finds a modern parallel in a storm of December 22-23, 1894, described by Köppen in the Annalen der Hydrographie, edited by the Naval Observatory at Hamburg, and published in Berlin. On the morning of December 22 the storm center, with a pressure of 715 mm., lay just east of Scotland; on the evening, with a pressure of 725, the center lay just west of Denmark. The whirling courses of the winds are well illustrated; a southerly gale crossed the Baltic, while a northerly gale raged on the North sea; violent east winds blew off the coast of Norway, and westerly gales were recorded in northern Germany. Disastrous storm floods were felt at many points on the coast, and salty rain fell at many points in England. Other storms were felt a week earlier and later; but, apropos of this ap

parent periodicity, Köppen remarks that thus far all efforts to establish weekly, monthly or longer weather cycles have, without exception, failed, and that, while the faint and easily obliterated traces of such periods have a certain scientific interest, they have not yet a practical value. The Annalen der Hydrographie is a characteristic German journal, in which a serious and scientific style of work is carried into the accounts of foreign coasts and harbors, as reported by officers of the marine. It frequently contains articles and reviews of interest on winds, tides and currents.

ELEVATION AS A CAUSE OF GLACIATION.

It is probable that no one questions the sufficiency of elevation to account for glaciation, if other things, such as external controls of climate, remain unchanged; but there are serious difficulties in the way of accepting the thesis maintained by Upham (latest expressed in Bull. Geol. Soc. Amer., vi., 1895, 343-352) to the effect that the glacial sheets of northeastern America and northwestern Europe were caused by and hence were coincident in time with the elevation that permitted the erosion of the deep marginal valleys of the continents. Upham cites the case of the Sogne fiord, on the west coast of Norway with a maximum sounding of 4,080 feet, as a measure of the epirogenic uplift which at its culmination caused the glaciation of northern Europe. The difficulty here is that while a comparatively long period of elevation must be postulated for the excavation of the valley of Sogne fiord, and while climatic change would respond immediately to elevation, yet glacial conditions are not known to have occured until the erosive effects of elevation were practically completed. The steepness of the fiord walls indicates that the elevation was not slowly progressive, but was rather promptly completed and steadily maintained; being in this unlike

the elevation by which the erosion of the flaring and benched valleys of the northern Alps has been allowed. The problem involved in the relation of elevation and glaciation would therefore seem to be not the simple one of immediate cause and effect, but on the other hand the difficult one of why the apparently competent cause should not have at once had its expected effect; why glaciation should have waited so long after elevation, not attaining its maximum until a time of depression.

FORESTS AND TORRENTS.

THE much-debated problem of the influence of forests on rainfall remains unproved, after all that has been said and done; but the influence of forests on torrents admits of no question. The soil is washed from the deforested slopes and the torrents spread it over the valleys, greatly to the injury of both high and low land. The Shenandoah Valley, for example, one of the most beautiful and productive farming districts in our country, is suffering along its margin from the encroachments of gravels and sands washed from the enclosing deforested ridges. Those who wish to present this matter to forestry meetings in popular and impres

sive form will find an abundance of illustrative material with references to European literature on the subject in an essay by Toula: Ueber Wildbach-Verheerungen and die Mittel ihnen vorzubeugen (Schr. Vereins zur Verbreitung naturw. Kenntnisse in Wien, xxxii., 1892, 499-622, with forty-one views from photographs). W. M. DAVIS.

HARVARD UNIVERSITY.

NOTES ON AGRICULTURE (III.)
THE EXPERIMENT STATION RECORD.

THE Experiment Station Record, a monthly (practically) published from the office of Experiment Stations of the U. S. Department of Agriculture gives under the heads of Chemistry, Botany, Zoöl

ogy, Meteorology, Soils, Fertilizers, Field crops, Horticulture, Forestry, Seeds, Weeds, Diseases of Plants, Entomology, Foods, Veterinary Science, Dairying, Technology, Statistics and Miscellaneous, the progress made in these various branches in the Experiment Stations of our country. The recent work in Agricultural Science in foreign countries is also briefly summarized.

From the last issue of the Record, just received, the reader is first of all informed as to the amounts of the appropriations made by Congress for the U. S. Department of Agriculture for the year ending June 30, 1896. The total amount is $2,578,750, which includes $720,000 for the Experiment Stations established under the act of Congress of March 2, 1887. There will be two new divisions in the U. S. Division

of Agriculture, namely, that of Agrostology, which contemplates 'field and laboratory investigation relating to the natural history, geographical distribution and use of the various grasses and forage plants,' and that of Soils.

Among reports of agricultural science in foreign lands is a paper upon ‘Agricultural Investigations in Switzerland,' by Dr. Grete, director of the Swiss Station at Zu

rich. In 1878 a Station for control of fertilizers and feeding stuffs was established, and recently its work has been extended to

include culture tests of soils. There is a Seed Control Station which at the present time has eight workers besides the director, and tests by germination thousands of samples of seeds.

Under the head of chemistry the Record gives the new methods of obtaining solutions in soil analyses and the determination of phosphoric acid. The department of Botany contains a review of Professor Scribner's 'Grasses' of Tennessee, which is a valuable contribution to the Agrostology of the whole country. Notes on Maize,' by Dr. Sturtevant, contains generalizations upon the